In semiconductor device processing, oxides of silicon are used in many different forms for many applications. Dense, thermally grown oxides of silicon are typically used as the primary gate dielectric film in MOS (metal oxide-silicon) transistors. Steam grown thermal oxides are commonly used as a field oxidation dielectric layer. Undoped chemically deposited oxides, such as tetraethylorthosilicate derived oxide (TEOS), produced by wet or vapor (CVD) processes are other types of dense oxides commonly encountered. Other forms of silicon oxide commonly encountered are porous. Examples include doped oxides such as phosphosilicate glass (PSG) and borophosphosilicate glass (BPSG), which are commonly used as inter-metal layer dielectrics because they can be easily planarized with an elevated temperature reflow process. Spin-on-glass (SOG) is another porous oxide used in dielectric applications where planarization is critical. A SOG is a siloxane-type polymer in an organic solvent which is deposited in liquid form and then cured at elevated temperature to form a solid silicon oxide film. Other porous silicon oxides commonly encountered include borosilicate glass (BSG), boron doped TEOS, phosphorous doped TEOS and boron/phosphorous doped TEOS (BP TEOS).
Many semiconductor device manufacturing processes require selective etching processes to allow for removal of one form of silicon oxide in preference to another form of silicon oxide or to another material.
It is known, from U.S. Pat. No. 4,749,440, to use anhydrous hydrogen fluoride gas in the presence of water vapor to effect silicon oxide removal. Using a commercial embodiment of this technology sold under the Excalibur(copyright) brand by FSI International, Chaska, Minn., U.S.A., selectivities between specific oxides such as phosphorous silica glass (PSG) and thermal oxide have been demonstrated up to 10,000:1.
It is further known from U.S. Pat. No. 5,635,102 to selectively remove a porous silicon oxide layer from a substrate by exposing the substrate to a flowing anhydrous gaseous environment consisting of anhydrous inert gas and adding anhydrous hydrogen fluoride gas to the gaseous environment for a pulse time which is at most only shortly longer than that required to initiate etching of the dense silicon oxide, flushing the gaseous environment with anhydrous inert gas for a time sufficient to remove the hydrogen fluoride and water vapor generated by the etching of the porous oxide and, repeating the adding and flushing steps until the porous oxide layer has been removed.
All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
The invention in various of its embodiment is summarized below. Additional details of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
The invention is directed in one embodiment to a method of selectively etching an in-process microelectronics device comprising the steps of providing an in-process microelectronics device comprising a first oxide and a second oxide, applying liquid water at a predetermined temperature to the surface of the in-process microelectronics device, removing a portion of the liquid water from the surface of the in-process microelectronics device, at least a portion of the liquid water remaining on the in-process microelectronics device, and selectively etching at least a portion of the surface of the in-process microelectronics device by applying anhydrous HF gas and optionally water vapor to the surface of the in-process microelectronics device. The temperature of the liquid water is predetermined to facilitate selectively etching one of the oxides relative to the other oxide during the selectively etching step.
The instant invention is further directed to a method of treating an in-process microelectronics device having at least one oxide thereon comprising the steps of providing an in-process microelectronics device having at least one oxide thereon, applying a liquid cleaning fluid to the surface of the in-process microelectronics device, the liquid cleaning fluid at a temperature above ambient, removing a portion of the liquid cleaning fluid from the surface of the in-process microelectronics device, at least a portion of the liquid cleaning fluid remaining on the surface of the in-process microelectronics device and applying anhydrous HF gas and optionally water vapor to the surface of the in-process microelectronics device to etch an oxide on the surface of at least a portion of the in-process microelectronics device.
The instant invention is further directed to a method for etching a surface of an in-process microelectronics device comprising the steps of positioning at least one in-process microelectronics device on a rotatable support, causing the rotatable support to rotate such that the in-process microelectronics device rotates around an axis, causing a heated liquid to contact and preheat the in-process microelectronics device as the in-process microelectronics device rotates about the axis and causing a gaseous etchant to etchingly contact the in-process microelectronics device as the in-process microelectronics device rotates about the axis.